Already I had searched on this but i did not understood so i asked to tell difference between set and Area with example. If anybody can tell me about this topic because just now I have started learning IDMS.

The Wikipedia article is pretty clear. An IDMS set is a one-to-many relationship between records. An IDMS area is a preformatted file (or part of a file or parts of multiple files) used to physically store the data. So a set is data while an area is a partitioning of the files.

Perhaps if you explained where you're having trouble with the concepts?

Logical Data Model:
...
The most distinctive structuring concept in the Codasyl model is the set. Not to be confused with a mathematical set, a Codasyl set represents a one-to-many relationship between records: one owner, many members. The fact that a record can be a member in many different sets is the key factor that distinguishes the network model from the earlier hierarchical model. As with records, each set belongs to a named set type (different set types model different logical relationships). Sets are in fact ordered, and the sequence of records in a set can be used to convey information. A record can participate as an owner and member of any number of sets.
...
Storage

IDMS organizes its databases as a series of files. These files are mapped and pre-formatted into so-called areas. The areas are subdivided into pages which correspond to physical blocks on the disk. The database records are stored within these blocks.

Now, if you don't know the difference between a 'logical data model'
and storage,
refer to my previous post.

Thanks, I got bit idea about SET, AREA and RECORD. An IDMS area is a preformatted file (or part of a file or parts of multiple files) Each area can contain occurrences of one or more record type. In the IDMS each entity like company, department and Employee along with their attribute are considered as record. IDMS support one too many relationship, this relationship is defined as set. Suppose for example if we consider Department and Employee set , its one too many relation one DEPARTMENT can have many employee. Department have its own record type like DEPT-ID,DEPT-NAME etc its record type. For example Set DEPARTMENT and EMPLOYEE may be found under same area or set DEPARTMENT may be under the area DEMO and EMPLOYEE may be under the area EMPL. Please correct me if my understand is wrong

You need to do a bit of reading, you've a link given to you and you have google as your friend. To start with, people around here expects, at least, you to have the basic knowledge of the matter you asked for. And if you don't know that and just starting with teh subject, you should at least show how many source of inforation you've already looked in - what manual did you refer and what makes you to raise your eye brows, with that kind of commitment many will be around to help you...fwiw.

Already i said just from 3 days i have started learning IDMS, I am not getting what exactly you are tellling. I told about set, area and record meaning thats all for that i am asking whether my understand is rite or wrong thats all

idms ( or any dbms ) datasets do not have any relation with those that You call flat files

flat files contain only application data
idms ( or any dbms ) datasets contain application data and control data
tha application data is what You see and use, control data is what is used by the dbms in order to provide its services

what is that You do not understand in the area explanation posted by Dick ??

areas are just containers not related in any way to the logical view of the application data